For anyone interested in building Java-based macOS universal applications, it is possible to create a bundled application that contains two Java runtimes, one for x86 and one for arm. A custom launcher is required to select the appropriate runtime based on the execution environment. I have created such a launcher; it is a very small modification of the macOS launcher used by jpackage.
The custom launcher is available on GitHub: https://github.com/violetlib/mac-universal-java-launcher There is some discussion of this issue in JDK-8266259 [https://bugs.openjdk.org/browse/JDK-8266259]. So far, there does not seem to be much interest in this topic. On a related note, is there a place where developers using Java on macOS who are not associated with OpenJDK can share information?
